Question 1

What is Förster Resonance Energy Transfer and how does it work?

Accepted Answer

Förster Resonance Energy Transfer (FRET) is a non-radiative transfer of energy between light-emitting molecules used to investigate close-range biochemical interactions. When an excited donor fluorophore is within 10 nm of an acceptor fluorophore, energy transfers via dipole-dipole interactions if their emission and absorption spectra overlap. The acceptor then emits light at its characteristic wavelength while donor emission decreases.

Question 2

Why is FRET called a molecular ruler?

Accepted Answer

FRET efficiency—the percentage of energy transferred from donor to acceptor—depends strongly on the distance between molecules. Since energy transfer only occurs within approximately 10 nm and efficiency decreases predictably with distance, FRET acts as a spectroscopic ruler. This distance-dependent property allows researchers to measure molecular proximity and detect conformational changes with nanometer-scale precision.

Question 3

How are biomolecules prepared for FRET experiments?

Accepted Answer

Biomolecules of interest, typically DNA or proteins, are engineered with fluorescent tags using molecular biology techniques. The modified genetic material is introduced into cells via transfection or electroporation. Samples are then prepared for visualization on a fluorescence microscope, either immobilized on slides for single-molecule FRET or loaded into wells for high-throughput screening.

Question 4

What happens to FRET signal when an enzyme cleaves a labeled substrate?

Accepted Answer

When an enzyme cleaves a substrate containing an active FRET pair, the donor and acceptor molecules separate beyond the 10 nm FRET range, disrupting energy transfer. This causes donor emission to increase and acceptor emission to decrease. By analyzing these emission changes and calculating direct emission factors, researchers can determine substrate concentration and kinetic parameters.

Question 5

How can FRET be used to monitor protein aggregation?

Accepted Answer

Cells are engineered to express monomers containing either component of a FRET pair. When aggregation is induced, monomers come within 10 nm of each other, generating a FRET response. This approach detects protein aggregation triggered by seeding with misfolded proteins. Cells are transduced with aggregates, incubated, and analyzed using flow cytometry to quantify the FRET signal.

Question 6

What data presentation methods are used in FRET experiments?

Accepted Answer

FRET data is presented in multiple ways depending on experimental goals. Color images show differences in emission intensity over time. Donor and acceptor emission intensities are plotted together to track FRET response. Data can also be fitted to various mathematical functions for complex analyses, making FRET a flexible tool for representing diverse experimental results.

Question 7

How does FRET detect conformational changes in protein sensors?

Accepted Answer

Protein sensors are prepared by labeling receptors with a FRET pair of fluorophores. The FRET response is monitored live using confocal microscopy. When conformational changes occur, fluorophores move in and out of the 10 nm FRET range, causing variations in emission wavelength and intensity. These changes directly indicate structural rearrangements in the protein.

Förster Resonance Energy Transfer (FRET) - Assessment Quiz